A mobile communication device and a method thereof. The mobile communication device includes a processor, a transceiver circuit, an amplifier circuit, and a control logic circuit. The processor generates a baseband signal and a gain control signal. The transceiver circuit converts the baseband signal to an analog form, and amplifies the converted baseband signal to output a first transmission signal. The amplifier circuit amplifies the first transmission signal to output a second transmission signal. The control logic circuit controls the transceiver circuit and the amplifier circuit based on the gain control signal to generate the second transmission signal. The transceiver circuit adopts one of a first plurality of power gain levels at an increasing sequence when the amplifier circuit adopts a lowest level of a second plurality of power gain levels.